Online Etymology Dictionary

em- (2): representing Latin ex- assimilated to following -m- (see ex-).
emaciate (v.): 1620s (implied in emaciating), from Latin emaciatus, past participle of emaciare "make lean, waste away," from ex- "out" (see ex-) + macies "leanness," from macer "thin" (see macro-). Related: Emaciated; emaciating.
emaciated (adj.): 1660s, past participle adjective from emaciate.
emaciation (n.): 1660s, from Latin emaciationem, noun of state from past participle stem of emaciare (see emaciate), or perhaps a native formation from emaciate.
emaculate (adj.): 1620s, from Latin emaculatus "freed from blemishes," past participle of emaculare, from ex- (see ex-) + maculare (see maculate (adj.)).
email (n.): a type of pottery design pattern, c.1877, from French email (12c.), literally "enamel" (see enamel (n.)).
emanant (n.): 1852, from Latin emanantem (nominative emanans), present participle of emanare (see emanate).
emanate (v.): 1680s, from Latin emanatus, past participle of emanare (see emanation). Related: Emanated; emanating.
emanation (n.): 1560s, from Late Latin emanationem (nominative emanatio), noun of action from past participle stem of Latin emanare "flow out, arise, proceed," from ex- "out" (see ex-) + manare "to flow," from PIE root *ma- "damp."
emancipate (v.): 1620s, from Latin emancipatus, past participle of emancipare "declare (someone) free, give up one's authority over," in Roman law, the freeing of a son or wife from the legal authority (patria potestas) of the pater familias, to make his or her own way in the world; from ex- "out, away" (see ex-) + mancipare "deliver, transfer or sell," from mancipum "ownership," from manus "hand" (see manual) + capere "take" (see capable). Related: Emancipated; emancipating. Adopted in the cause of religious toleration (17c.), then anti-slavery (1776). Also used in reference to women who free themselves from conventional customs (1850).
emancipation (n.): 1630s, "a setting free," from French émancipation, from Latin emancipationem (nominative emancipatio), noun of action from past participle stem of emancipare (see emancipate). Specifically with reference to U.S. slavery from 1785. In Britain, with reference to easing of restrictions on Catholics, etc.
emancipator (n.): 1782, agent noun in Latin form from emancipate.
emancipatory (adj.): 1650s; see emancipate + -ory.
emasculate (v.): c.1600, from Latin emasculatus, past participle of emasculare "castrate," from ex- "out, away" (see ex-) + masculus "male, manly" (see masculine). Originally and usually in a figurative sense. Related: Emasculated; emasculating.
emasculation (n.): 1620s, agent noun from emasculate.
embalm (v.): mid-14c., from Middle French embaumer "preserve (a corpse) with spices," from en- "in" (see en- (1)) + baume "balm" (see balm) + -er verbal suffix. The -l- inserted in English 1500s in imitation of Latin. Related: Embalmed; embalming.
embankment (n.): 1786, from embank "to enclose with a bank" (1570s; see bank (n.2)) + -ment.
embargo (n.): 1590s, from Spanish embargo "seizure, embargo," noun of action from embargar "restrain impede," from Vulgar Latin *imbarricare, from in- "into, upon" (see in- (2)) + *barra (see bar (n.1)). As a verb, from 1640s. Related: Embargoed.
embark (v.): 1540s, from Middle French embarquer, from em- (see en- (1)) + barque "small ship" (see bark (n.)). Related: Embarked; embarking.
embarkation (n.): 1640s, from French embarcation, noun of action from embarquer (see embark).
embarras (n.): 1660s, from French embarras "obstacle;" see embarrass.
embarrass (v.): 1670s, "perplex, throw into doubt," from French embarrasser (16c.), literally "to block," from embarras "obstacle," from Italian imbarrazzo, from imbarrare "to bar," from in- "into, upon" (see in- (2)) + Vulgar Latin *barra "bar."

Meaning "hamper, hinder" is from 1680s. Meaning "make (someone) feel awkward" first recorded 1828. Original sense preserved in embarras de richesse (1751), from French (1726): the condition of having more wealth than one knows what to do with. Related: Embarrassed; embarrassing; embarrassingly.
embarrassed (adj.): "perplexed, confused," 1680s, past participle adjective from embarrass.
embarrassment (n.): 1670s, "state of being impeded, obstructed, entangled" (of affairs, etc.), from embarrass + -ment, or from French embarrassement, from embarrasser.

As "a mental state of unease," from 1774. Meaning "thing which embarrasses" is from 1729. Earlier words expressing much the same idea include baishment "embarrassment, confusion" (late 14c.); baishednesse (mid-15c.).
embassador (n.): identified by OED as a variant of ambassador "still preferred" in the U.S.
embassy (n.): 1570s, "position of an ambassador," from Middle French embassee "mission, charge, office of ambassador," Old French ambassee, from Italian ambasciata, from Old Provençal ambaisada "office of ambassador," from Gaulish *ambactos "dependant, vassal," literally "one going around," from PIE *amb(i)-ag-to, from *ambi- (see ambi-) + *ambi- "around" (see ambi-) + *ag- "to drive, move" (see act (n.)).

Meaning "official residence and retinue of an ambassador" is from 1764. In earlier use were embassade (late 15c.), ambassade (early 15c.).
embattle (v.): late 14c., "prepare for a fight," from Old French embataillier "to prepare for battle," from en- (see en- (1)) + bataille (see battle (n.)). Related: Embattled; embattling. Originally of armies; of individuals as well since 1590s (first attested in Spenser).
embattled (adj.): "under attack," by 1882; earlier it meant "prepared to fight," and (of structures) "fitted with battlements;" past participle adjective from embattle (v.).
embed (v.): 1778, from em- + bed (n.). Originally a geological term, in reference to fossils in rock; figurative sense is from 1835; meaning "place a journalist within a military unit at war" is 2003. Related: Embedded; embedding.
embellish (v.): mid-14c., "to render beautiful," from Old French embelliss-, stem of embellir "make beautiful, ornament," from em- (see en- (1)) + bel "beautiful," from Latin bellus (see bene-). Meaning "dress up (a narration) with fictitious matter" is from mid-15c. Related: Embellished; embellishing.
embellishment (n.): 1590s, from embellish + -ment.
ember (n.): Old English æmerge "ember," merged with or influenced by Old Norse eimyrja, both from Proto-Germanic *aim-uzjon- "ashes" (cf. Middle Low German emere, Old High German eimuria, German Ammern); a compound from *aima- "ashes" (from PIE root *ai- "to burn;" see edifice) + *uzjo- "to burn" (from PIE root *eus- "to burn;" cf. Latin urere "to burn, singe"). The -b- is intrusive.
ember days (n.): Old English Ymbrendaeg, Ymbren, 12 days of the year (divided into four seasonal periods, hence Latin name quatuor tempora) set aside by the Church for fasting and prayers, from Old English ymbren "recurring," corruption of ymbryne "a circuit, revolution, course, anniversary," literally "a running around," from ymb "round" (cognate with Greek amphi, Latin ambo; see ambi-) + ryne "course, running" (see run (n.)). Perhaps influenced by a corruption of the Latin name (cf. German quatember).
embergoose (n.): "loon," 1744, from Norwegian emmer-gaas, perhaps so called from its appearing on the coast in the ember days before Christmas.
embezzle (v.): early 15c., from Anglo-French embesiler "to steal, cause to disappear" (c.1300), from Old French em- (see en- (1)) + besillier "torment, destroy, gouge," of unknown origin. Sense of "to dispose of fraudulently" is first recorded 1580s. Related: Embezzled; embezzling.
embezzlement (n.): 1540s, from embezzle + -ment.
embezzler (n.): 1660s, agent noun from embezzle.
embitter (v.): c.1600, from em- + bitter. Now rare in its literal sense; figurative meaning first attested 1630s. Related: Embittered.
emblazon (v.): "inscribe conspicuously," also "extol," 1590s, from en- (1) + blazon. Related: Emblazoned; emblazoning.
emblem (n.): 1580s, from French emblème "symbol" (16c.), from Latin emblema "inlaid ornamental work," from Greek emblema (genitive emblematos) "embossed ornament," literally "insertion," from emballein "to insert," literally "to throw in," from en "in" (see en- (2)) + ballein "to throw" (see ballistics).
emblematic (adj.): 1640s, perhaps via French emblématique, from Greek emblematikos, from emblema (see emblem).
embodiment (n.): 1828; see embody + -ment.
embody (v.): 1540s, in reference to a soul or spirit invested with a physical form; of principles, ideas, etc., from 1660s; from en- (1) "in" + body. Related: Embodied; embodying.
embolden (v.): 1570s, from en- (1) + bold + -en (1). Related: Emboldened.
embolism (n.): late 14c., "intercalation of days into a calendar," from Old French embolisme, from Late Latin embolismus "insertion of days in a calendar to correct errors," from Greek embolimos, embolme "insertion," or embolos "a plug, wedge" (see embolus). Medical sense of "obstruction of a blood vessel" is first recorded in English 1855.
embolus (n.): 1660s, "stopper, wedge," from Latin embolus "piston of a pump," from Greek embolos "peg, stopper; anything pointed so as to be easily thrust in," also "a tongue (of land), beak (of a ship)," from emballein (see emblem). Medical sense is from 1866. Related: Embolic.
embonpoint (n.): "plumpness," 1751, from French embonpoint (16c.), from Old French en bon point, literally "in good condition."
emboss (v.): late 14c., from Old French *embocer (cf. embocieure "boss, stud, buckle"), from em- (see en- (1)) + boce "knoblike mass" (see boss (n.2)). Related: Embossed; embossing.
embouchure (n.): 1760, in musical sense, from French embouchure "river mouth, mouth of a wind instrument," from en- "in" (see en- (1)) + bouche "mouth" (see bouche).
embrace (v.): mid-14c., from Old French embracer (12c., Modern French embrasser) "clasp in the arms, enclose; covet, handle, cope with," from en- "in" (see en- (1)) + brace, braz "the arms," from Latin bracchium (neuter plural brachia); see brace (n.). Related: Embraced; embracing; embraceable. Replaced Old English clyppan, also fæðm.